I know this post is very unlikely to change anyone's opinions of the GO mCCR, but after diving it from the prototype stage to the production unit, I would like to weigh in. Personally, I have been diving rebreathers for over twenty years and teaching them for 18 years. I am currently certified on 14 different units and an instructor on eight of those. I only say this as an attempt to show I have been on lots of rebreathers, both eCCR and mCCR, and I fully appreciate that there is no perfect rebreather. If there was, it would be the only one on the market and the others would simply go away.
As has been mentioned above, the GO was designed by Mike Young of KISS and is an mCCR with the same physics as the KISS units, meaning a constant mass flow unit that is "depth limited" to around 300 fsw as the intermediate pressure of the first stage is fixed at about 147 psi (10 ATA). While it can be dived to these depths, it has a smaller scrubber of about 3.5 pounds and it has initially been marketed to the recreational diver who is nitrox certified and wants to get into rebreathers. For those divers there is a CCR Diver certification that limits the diver to 100 feet with no decompression. There is also a CCR Decompression Diver certification to 40 meters with deco for the diver with Advanced Nitrox/Decompression Procedures certification. A 60 meter course is being developed. There are no plans for a 100m deep course as it is felt this is simply not the right tool for that type of diving. The scrubber duration and work of breathing have undergone independent testing and the GO has fared EXTREMELY well. It is the smaller amount of scrubber, not the physics, the design, or the work of breathing that has made Mike Young and Dive Talk feel it should be limited to 60m of depth.
Also, as has been mentioned above, there are a multitude of other chest mount rebreathers out there so what makes this one different? The main difference as I see is its small size and the improved work of breathing by moving the counterlungs from the "front" to the "sides" of the unit. This places the counterlungs very close to the position of your lungs and makes the work of breathing very good. The circular axial scrubber design with its large surface area but relatively thin bed also improves the work of breathing. It is also a very small unit, smaller than the profile of, say, the Choptima and lighter as well. However, it only has 3.5 pounds of scrubber material, and does not take an ExtendAir cartridge. So, if you are traveling to a place with oxgyen but no sorb readily available, taking a Choptima and throwing in a couple of ExtendAir cartridges is probably a better option. In that case, I'd trade the larger size, the increased weight, and the front mounted counterlungs for the convenience of taking my own ExtendAir cartridges. Like I said, no rebreather is perfect. They all have their pros and cons.
All training on the GO is being done through Dive Talk Academy. After consulting with an attorney who is VERY involved in the rebreather industry, Dive Talk decided to only train through their own agency, Dive Talk Academy, so they can better control instructor quality and quality of training. While being initially marketed as a "recreational rebreather", they have NOT shortcut the training. The training standards are directly from RESA (Rebreather Education and Safety Association) recommendations to the other training agencies. Initial training for a CCR No-Decompression Diver on the GO requires the same 60 minutes of confined water training followed by 7 dives and 420 minutes of open water training as with other agencies such as TDI, IANTD, etc. All of the usual rebreather skills and drills are required -- hypoxia, hyperoxia, hypercapnia, boom scenarios, open circuit bailouts, SCR, etc. While it is being initially marketed as a "recreational" rebreather, the training standards are excellent (in my opinion). Combining that with hand-picked instructors and instructor trainers should make for quality training. For transparency, yes, I am one of the three current instructor trainers on the unit, along with Mike Young and Edd Sorensen. We are in the process of selecting and training instructors around the country. There are no plans to spend the money to get CE approval in Europe at the moment.
So, what is the "niche" for this rebreather in my opinion? Personally, I love recreational diving, but prefer some of the benefits of rebreathers (quiet, no bubbles, warm/moist gas, long no-decompression times, etc) over open circuit. With this unit, I can go on a two tank recreational boat charter with an AL63 (or AL80 if that's all they have) of air, set up my kit with my usual BCD and my usual regulator (with one additional LP hose to connect to the rebreather), and just clip on this rebreather. I can do the two one hour dives without changing tanks and only going through a couple of hundred psi of air over the two hours of diving. If the trip is a "double dip", I can do one long dive on the GO. If I am shore diving in Bonaire, I can easily do a single two hour dive with an AL63. If someone has back issues, this CCR can be used easily in a sidemount configuration with a single AL40. The AL40 and the CCR can be handed up to the crew and the diver can simply walk up the boat ladder wearing only a sidemount harness. Granted, I could do the same thing on a Choptima or several other chest mount rebreathers, but the GO is a smaller, lighter, and less expensive option for this type of diving.
Could this unit be used for deeper diving, technical diving, or cave diving? Certainly. However, in my opinion, there are better tools for that type of diving. So, if you are looking to do deep technical dives or cave diving, there are better choices for you than the GO. Personally, for cave diving I prefer my Sidewinder and for deep ocean diving, I like my Spirit or my Choptima. However, if what you are interested in is diving to recreational limits but with the benefits of rebreathers mentioned above in a very small lightweight versatile package, you should consider the GO.
Just my 2 cents.
